ABSTRACT
This chapter gives a global summary of diagnostic possibilities in cases of suspected nonimmediate (delayed) cutaneous adverse drug reactions, aimed at readers inexperienced in this field of medicine. Diagnostic procedures include patch tests, prick tests, intradermal tests, drug provocation tests and in vitro tests such as the lymphocyte transformation test (LTT). Given the scope of the book, the emphasis is on patch testing; the discussion of the other tests is limited. Whereas patch testing appears to be mostly a safe diagnostic procedure in all drug reactions, including the severe types (acute generalized exanthematous pustulosis [AGEP], drug reaction with eosinophilia and systemic symptoms [DRESS], Stevens-Johnson syndrome [SJS], toxic epidermal necrolysis [TEN], and generalized bullous fixed drug eruption [GBFDE]), intradermal tests and oral drug provocation tests may sometimes be (very) dangerous to the patient and is an established contraindication in certain conditions.
